Athlon 2600+, 1 GB of RAM, video card ATI Radeon 5220 – a rather basic configuration. The slowdowns first appeared on already opened maps, filled with “various textured elements” (forests, etc.). I fixed it by changing the camera angle on the map, i.e., by rotating the mouse while holding down the left button. The view became more vertical, but the slowdowns on such maps disappeared. By the way, the game settings are at a medium level. Maybe this will be useful to someone. Fight on! :D